The present invention relates to an integrated circuit configuration having a structure for reducing a minority charge carrier current.
In integrated circuit configurations, in particular, in integrated circuit configurations in which a vertical power component and a control or processing circuit are integrated in a semiconductor body, it is adequately known that, under specific operating states determined by the external circuitry, the power component can inject minority charge carriers into the substrate or into an epitaxial layer applied to the substrate, which do not flow away through the terminals of the power component. These charge carriers injected into the substrate or the epitaxial layer can propagate there and disturb the control or processing circuit unless suitable measures are taken to prevent such propagation.
German Patent DE 42 09 523 C1 discloses disposing an annular structure in an epitaxial layer on a substrate around a component region that potentially injects minority charge carriers. The structure includes a heavily doped zone of the same conduction/conductivity type as the substrate, which reaches from a front side of the semi-conductor body as far as the substrate, and a heavily doped zone of a complementary conductivity type with respect to the doping of the substrate, which, likewise, reaches as far as the substrate proceeding from the front side, the two zones being short-circuited. If, in the case of this configuration, charge carriers are injected into the substrate, then a current flow in the annular structure pulls the substrate to a lower potential in order to reduce the injection of charge carriers.
Comparable structures for reducing the propagation of minority charge carriers or the injection of minority charge carriers are described in U.S. Pat. No. 5,719,431 to Werner and European Patent Application EP 0 725 442, corresponding to U.S. Pat. No. 5,942,783 to Brambilla et al.
It is accordingly an object of the invention to provide an integrated circuit configuration having a structure for reducing a minority charge carrier current that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that has a structure for reducing a propagation of minority charge carriers.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an integrated circuit configuration, including a semiconductor body having a rear side, a front side, a first semiconductor zone of a first conductivity type in a region of the rear side, and a second semiconductor zone of the first conductivity type adjoining the first semiconductor zone, the second semiconductor zone doped weaker than the first semiconductor zone and disposed in a region of the front side, a first component region in the semiconductor body having at least one semiconductor zone of a second conductivity type, a second component region in the semiconductor body having at least one semiconductor zone of the second conductivity type, and a conversion structure having a first structure semiconductor zone of the second conductivity type and a second structure semiconductor zone of the first conductivity type, the first structure semiconductor zone and the second structure semiconductor zone being short-circuited and respectively disposed at a distance from the first semiconductor zone in the second semiconductor zone between the first and second component regions.
The first semiconductor zone represents a semiconductor substrate, for example, and the second semiconductor zone and epitaxial layer applied to the semiconductor substrate. A first component region, which has at least one semiconductor zone of a second conductivity type, and a second component region, which has at least one semiconductor zone of the second conductivity type, are formed in the semiconductor body. To prevent or at least reduce the propagation of minority charge carriers in the second semiconductor zone, there is a conversion structure present between the first and second component regions in the second semiconductor zone, the conversion structure having a semiconductor zone of the second conductivity type and a semiconductor zone of the first conductivity type, which are short-circuited and which are, in each case, disposed at a distance from the first semiconductor zone between the first and second component regions in the second semiconductor zone.
The semiconductor zone of the second conductivity type in the second semiconductor zone in the first component region is, preferably, part of a vertical semiconductor component having at least a first and a second terminal electrode, the first terminal electrode being connected to the first semiconductor zone and the second terminal electrode being connected to the semiconductor zone of the second conductivity type.
If, in the case of the semiconductor component according to the invention, minority charge carriers are injected into the second semiconductor zone, then, they are taken up by the conversion structure and converted into majority charge carriers that are injected into the second semiconductor zone again. The majority charge carriers can, then, flow away through the terminal electrodes. By converting the minority charge carriers into majority charge carriers, the conversion structure prevents the propagation of minority charge carriers in the second semiconductor zone, which might otherwise pass to zones of the second conductivity type in the second component region and influence the functioning of components realized there.
The power component in the first component region may be configured as a diode, the first semiconductor zone or the semiconductor substrate forming the cathode in the case of n-type doping and the zone of the second conductivity type, which is then p-doped, forming the anode.
The power component may also be configured as a MOS transistor, in which case at least one further zone of the first conductivity type is disposed in the zone of the second conductivity type and a gate electrode is present that is insulated from the zone of the first conductivity type and the zone of the second conductivity type. The zone of the second conductivity types forms the body zone of the MOS transistor, which is short-circuited with the zone of the first conductivity type, which forms the source zone, by a source electrode. The first semiconductor zone forms the drain zone of the MOS transistor.
A MOS transistor as power component injects minority charge carriers into the second semiconductor zone, which serves as a drift path, if it is operated in the reverse direction, that is to say, if the potential at the source terminal is lower than at the drain terminal and the internal body diode, thus, turns on. The minority charge carriers are holes in the case of an n-conducting transistor.
A diode as power component injects minority charge carriers if it is operated in the forward direction.
In accordance with another feature of the invention, there are provided semiconductor zones of the first conductivity type connected to the first terminal electrode, the semiconductor zones disposed in the at least one semiconductor zone of the second conductivity type in the second semiconductor zone.
In accordance with a further feature of the invention, there is provided a control electrode in the first component region insulated from the semiconductor body adjacent the at least one semiconductor zone of the second conductivity type and at least one of the semiconductor zones of the first conductivity type, the at least one semiconductor zone being formed in the at least one semiconductor zone of the second conductivity type.
In accordance with an added feature of the invention, there is provided at least one further semiconductor zone of the first conductivity type disposed in the at least one semiconductor zone of the second conductivity type in the second semiconductor zone in the first component region.
In accordance with an additional feature of the invention, at least two of the semiconductor zones of the first conductivity type are disposed in the at least one semiconductor zone of the second conductivity type in the second semiconductor zone in the first component region.
In accordance with yet another feature of the invention, the zone of the first conductivity type and the zone of the second conductivity type of the conversion structure directly adjoin one another, while they are disposed at a distance from one another in the case of a further embodiment. The short circuit between these two zones is, preferably, formed by a layer made of a metal or polysilicon, which is applied to the front side of the semiconductor body.
Moreover, in accordance with yet a further feature of the invention, the zone of the second conductivity type of the conversion structure extends, proceeding from the front side of the semiconductor body, further into the semiconductor body in the vertical direction than the zone of the first conductivity type of the conversion structure.
Preferably, a plurality of conversion structures with in each case a zone of a first conductivity type and a zone of a second conductivity type are disposed next to one another between the first and second component regions.
To obtain a particularly good effect of the conversion structure, in accordance with a concomitant feature of the invention, the conversion structure is formed annularly around the first component region in which minority charge carriers are potentially injected.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an integrated circuit configuration having a structure for reducing a minority charge carrier current, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.